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  • Polymer and Materials Science  (14)
  • Acanthaceae  (2)
  • 11
    Electronic Resource
    Electronic Resource
    Cross-Linking efficiency of styrene-butadiene rubber with dicumyl peroxide and evaluation of interaction parameter (1967)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 109 (1967), S. 217-230 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Vernetzerwirksamkeit von Dicumylperoxid bei Styrol-Butadiengummi (SBR-1507) wurde mit Hilfe von Quellungsmessungen erfaßt. Die erhaltenen Werte sind 2,5 bzw. 5 für ungereinigten bzw. gereinigten SBR. Der niedrigere Wert im ersten Fall wurde der Vernichtung von Peroxyradikalen durch Antioxydantien im Gummi zugeschrieben. Die physikalischen Vernetzungen, die beim gereinigten SBR auf Kettenverknäuelungen zurückzuführen sind, betragen 0,14.10-4 Mol/g Gummi (oder 0,07.10-4 Vernetzungsstellen der Kettenverknäuelungen/g Gummi). Die Löslichkeitsparameter für gereinigten SBR aus Quellungs- und Viskositätsmessungen betragen 8.45 (kcal/ml)1/2 bzw. als Kohäsionsenergiedichte 71,403 kcal/ml. Mit diesem Wert des Löslichkeitsparameters wird der Lösungsmittel-Polymer-Wechselwirkungsparameter berechnet und durch die Methode von HUMMEL bestätigt. Der Durchschnittswert beträgt 0,37.
    Notes: The cross-linking efficiency of dicumyl peroxide with styrene-butadiene rubber (SBR-1507) has been measured by the swelling method. The values are found to be 2.5 and 5.0 for unpurified and purified SBR, respectively. The lower value in the former case has been ascribed to the destruction of peroxy radicals by the antioxidants present in the rubber. The physical cross-links due to chain entanglement for purified SBR are found to be 0.14 . 10-4 mole/g of rubber (0-07.10-4 cross-links due to chain entanglement/g of rubber). The solubility parameter for purified SBR as determined from both swelling and viscosity measurements is found to be 8.45 (kcal/ml)1/2 or cohesive energy density as 71.403 kcal/ml. Using this value of the solubility parameter, the solvent-polymer interaction parameter is calculated and is further verified by HUMMEL'S method. The average value is found to be 0.37.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1967.021090119
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  • 12
    Electronic Resource
    Electronic Resource
    Synthesis of a poly(terephthaloylphosphine) (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 1-6 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(phenylphosphindiylterephthaloyl), ein neues phosphorhaltiges Polymeres, wurde durch Lösungspolykondensation von Dilithium(phenyl)phosphin mit Terephthaloylchlorid bei niedriger Temperatur hergestellt. Es ist in polaren aprotischen Lösungsmitteln löslich; die inhärente Viskosität in DMF bei 30°C beträgt 19 ml/g. Das Polymere wurde mittels Elementaranalyse sowie IR- und 1H-NMR-Spektroskopie charakterisiert. TGA-Messungen ergeben, daß das Polymere in Luft bis 250°C stabil ist; es ist selbstverlöschend.
    Notes: Poly(phenylphosphinediylterephthaloyl), a novel phosphorus-containing polymer, was synthesized by low-temperature solution polycondensation of dilithio(phenyl)-phosphine with terephthaloyl chloride. The resulting polymer is soluble in polar aprotic solvents, having inherent viscosity of 19 ml/g in DMF at 30°C. The polymer was characterized by elemental analysis, IR and 1H-NMR spectroscopy. TGA data show that the polymer is stable up to 250°C in air. The polymer was found to be self-extinguishing.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051990101
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  • 13
    Electronic Resource
    Electronic Resource
    Studies of vulcanization with tetramethylthiuram disulfide and sulfur vulcanization accelerated by tetramethylthiuram disulfide of styrene-butadiene rubber in presence and absence of dicumyl peroxide (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 2255-2268 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The salient features of nonelemental sulfur vulcanization by tetramethylthiuram disulfide (TMTD) and elemental sulfur vulcanization promoted by TMTD both in presence and absence of ZnO and stearic acid have been studied. In stock containing TMTD, a higher rate constant value for dicumyl peroxide (DCP) decomposition was observed. TMTD decreases the crosslinking density due to DCP depending on its concentration. An entirely radical mechanism has been advanced in the absence of ZnO. ZnO or ZnO-stearic acid seems to alter the entire course of reaction. The rate of crosslinking increases in the presence of ZnO or ZnO-stearic acid. Moreover, crosslinks are formed additively (further supported from the activation energy data), and mixed crosslink formation has been confirmed by the methyl iodide test of the vulcanizates. Stearic acid has no effect on crosslink formation. An ionic chain mechanism has been postulated in the presence of ZnO, as suggested by British authors.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150916
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  • 14
    Electronic Resource
    Electronic Resource
    Studies of accelerated sulfur vulcanization of styrene-butadiene rubber by N-cyclohexylbenzothiazol-2-sulfenamide in the presence and absence of dicumyl peroxide (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 2773-2784 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study embodies the results and discussion of a comprehensive and systematic investigation of the mechanism of sulfuration of styrene-butadiene rubber accelerated by N-cyclohexylbenzothiazole-2-sulfenamide (CBS) with and without activators. Dicumyl peroxide (DCP) has been taken as a chemical aid to distinguish between free-radical and polar mechanisms of sulfuration. The rate constant for DCP decomposition in presence of CBS and the reduction in crosslink density by CBS have also been studied. With a constant amount of DCP and sulfur the crosslink density increases with increasing CBS concentration. In the presence of ZnO and stearic acid, crosslinking proceeds faster than in a similar system without these ingredients, and with DCP the crosslinks are found to be formed nearly additively as confirmed by methyl iodide treatment of the vulcanizates. In the absence of DCP, the crosslinking is characterized by an induction period, even in presence of ZnO and stearic acid. In the presence of sulfur, the 2-mercaptobenzothiazole (MSH) or amine or amine salt form crosslinkins by ionic reaction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170151121
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  • 15
    Electronic Resource
    Electronic Resource
    Studies on diphenylguanidine-accelerated sulfur vulcanization of styrene butadiene rubber in the presence and absence of dicumylperoxide (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 2971-2983 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diphenylguanidine (DPG) raises the rate of decomposition of dicumylperoxide (DCP) and the crosslinking maxima due to DCP is lowered to some extent by DPG. When the molar proportion of DPG-S is approximately 1:1, no additive results of crosslink formation (as reported for NR) are observed. Zinc oxide and stearic acid increase the rate of crosslinking as well as the crosslinking maxima. In the present study it appears most probable that DPG-accelerated sulfuration of SBR is an ionic process. At a constant level of DCP and sulfur crosslink density increases when the amount of DPG is increased; a constant level of DCP and DPG crosslinking increases with rising sulfur concentration.An increase in the concentration of DPG or sulfur leads to greater formation of the complex as well as a change in its composition. The effect of DPG is more pronounced, for by reducing the number of sulfur atoms more sulfur is available for crosslinking. Sulfur absorbs little SO2 or H2S; if it is already saturated, there is no perceptible effect. DPG does absorb H2S or SO2 and the rate and maxima of crosslinks is increased. The effect of SO2 is higher because of the higher Ka values of H2SO3 and consequently higher concentration of HSO3-. Reversion is a free-radical process inhibited by free DPG present in the system. In the presence of zinc oxide and stearic acid the reaction follows a polar mechanism as well as a radical mechanism.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.170161122
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  • 16
    Electronic Resource
    Electronic Resource
    On the partial mercerization and crimp development in jute fiber (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 21 (1983), S. 263-270 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.130210406
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